Ecology and natural history of Akodon lindberghi (Rodentia, Sigmodontinae) in southeastern Brazil

We studied the ecology and natural history of the globally threatened and poorly known Akodon lindberghi Hershkovitz, 1990 in Parque Nacional da Serra da Canastra (PNSC) and Juiz de Fora (JF), southeastern Brazil. From November 1998 to September 2001 a total of 131 individuals were captured in wire-cage live-traps and 52 by pitfalls traps. They were all marked and released at the site. The largest abundances were registered during the dry season, and most of the captures occurred in open habitats. The mean body mass of the two populations was significantly different (18.1 g at PNSC versus 13.1 g at JF; H = 46.2678, g.l.=2, p<0.001). In PNSC, individuals were reproductively active from August to February, and juveniles were present from May to August. The results suggest that the changes in vegetation structure caused by deforestation and intensive agricultural activities could increase the predation rate, affecting the mean body mass of the population.

Dieta rica em proteína na redução do peso corporal

A proporção ideal dos macronutrientes em dietas de emagrecimento é atualmente bastante discutida. Existem evidências de que dietas com maior proporção de proteína aumentam a perda de peso e de gordura corporal e diminuem a perda de massa corporal magra durante o emagrecimento. Todavia, os mecanismos responsáveis por estes efeitos não estão totalmente esclarecidos. Além disso, existem poucas conclusões a respeito dos possíveis efeitos colaterais dessas dietas na função renal e no estado nutricional relativo ao cálcio. Assim, este artigo objetiva trazer informações atuais sobre os efeitos de dietas ricas em proteína na perda de peso e na composição corporal e dos mecanismos envolvidos, bem como seus efeitos na função renal e no estado nutricional relativo ao cálcio.

Anticorpos contra LDL-ox e síndrome coronariana aguda

FUNDAMENTO: A oxidação da lipoproteína de baixa densidade (LDL-ox) induz à formação de epítopos imunogênicos na molécula. A presença de autoanticorpos contra a LDL-ox tem sido demonstrada no soro de pacientes com doença arterial coronariana (DAC). Contudo, o papel desses autoanticorpos na fisiopatologia das síndromes coronarianas agudas (SCA) e o seu significado clínico permanecem indefinidos. OBJETIVO: Avaliar a associação entre autoanticorpos contra a LDL-ox e SCA. MÉTODOS: Os títulos de imunoglobulina G autoanticorpos contra a LDL-ox por cobre (antiLDL-ox) e contra o peptídeo sintético D derivado da apolipoproteína B (antipeptD) foram determinados por ensaio imunoenzimático (ELISA) em 90 pacientes, nas primeiras 12h de SCA (casos) e em 90 pacientes com DAC crônica (controles). RESULTADOS: Os resultados mostraram que os títulos de antiLDL-ox foram significativamente mais elevados (p = 0,017) nos casos (0,40 ± 0,22), do que nos controles (0,33 ± 0,23). Por outro lado, os títulos de antipeptD foram significativamente menores (p < 0,01) nos casos (0,28 ± 0,23) do que nos controles (0,45 ± 0,30). A diferença dos títulos de ambos anticorpos entre os dois grupos estudados foi independente de idade, sexo, hipertensão arterial, diabete melito, dislipidemia, índice de massa corporal, tabagismo, perfil lipídico, uso de estatinas e história familiar de DAC. CONCLUSÃO: Os resultados mostraram que os títulos de antiLDL-ox foram significativamente mais elevados nos pacientes com síndrome coronariana aguda quando comparados aos pacientes com doença arterial coronariana e podem estar associados à instabilidade da placa aterosclerótica.

Medidas murinométricas e eficiência alimentar em ratos provenientes de ninhadas reduzidas na lactação e submetidos ou não ao exercício de natação

INTRODUÇÃO: Excesso de alimentação no início da vida pode modificar persistentemente consumo e peso corporal. Adoção de exercício físico é uma estratégia útil para evitar excessivo ganho de peso. OBJETIVO: Avaliar o crescimento corporal e a eficiência alimentar em ratos provenientes de ninhada reduzida no aleitamento. MÉTODOS: Ao terceiro dia de vida, ninhadas foram formadas com quatro (GN4) ou 10 animais (GN10), (n = 25). Ao desmame, ratos machos Wistar permaneceram em gaiolas individuais, e, aos 60 (± 2) dias foram subdivididos em sedentários (SED) e exercitados (NAT), formando quatro grupos: GN4SED, GN10SED, GN4-NAT e GN10NAT. Avaliou-se o peso, ganho de peso e taxa específica de ganho de peso, gordura epididimal, índices de massa corporal e Lee, consumo e eficiência alimentar, glicemia e lactemia. RESULTADOS: Aos 21 dias, o GN4 apresentava peso corporal 52% acima do GN10 (P = 0,001). Contudo, aos 30 e 60 dias os pesos não diferiram. Ao final do período, GN10NAT demonstrou menor peso (356,82 ± 23,04) que GN10SED (409,28 ± 17,30). Mas GN4NAT possuía maior peso (417,85 ± 37,91) que GN4SED (413,69 ± 57,45) e GN10NAT. O GN4 exibiu elevada taxa de ganho de peso na lactação, mas, redução da mesma pós-desmame. Independente do tamanho da ninhada, a taxa de ganho de peso reduz com o aumento da idade. Ao final do período, glicemia, gordura epididimal total e relativa, e os índices de Lee e IMC não diferiram entre os grupos. Os valores de lactato antes e após o exercício condizem com esforço de intensidade moderada. Na periadolescência, GN4 apresentou menor ingestão de alimentos, mas sem diferenças na vida adulta. CONCLUSÃO: A redução da ninhada no aleitamento não alterou o peso corporal ou ingestão alimentar persistentemente. Entretanto, o protocolo de natação foi eficaz em reduzir o ganho de peso em animais controles, mas não naqueles de ninhada reduzida.

Aerobic and anaerobic metabolism for the zebrafish, Danio rerio, reared under normoxic and hypoxic conditions and exposed to acute hypoxia during development

In order to verify the influence of chronic and acute ambient oxygen levels from egg to adult stage of the zebrafish, in vivo oxygen consumption (MO2), critical tensions of oxygen (Pcrit), heart rate (fH) and total body lactate concentration (Lc) were determined for Danio rerio (Hamilton, 1822) raised at 28 °C under normoxic (7.5 mgO2.L-1 or 80 mm.Hg-1) and hypoxic conditions (4.3 mgO2.L-1) and exposed to acute hypoxia during different developmental stages. Our findings confirmed that very early stages do not respond effectively to ambient acute hypoxia. However, after the stage corresponding to the age of 30 days, D. rerio was able to respond to acute hypoxia through effective physiological mechanisms involving aerobic and anaerobic metabolism. Such responses were more efficient for the fishes reared under hypoxia which showed that D. rerio survival capability increased during acclimation to mild hypoxia. Measurements of body mass and length showed that moderate hypoxia did not affect growth significantly until the fish reached the stage of 60 days. Moreover, a growth delay was verified for the hypoxic-reared animals. Also, the D. rerio eggs-to-larvae survival varied from 87.7 to 62.4% in animals reared under normoxia and mild hypoxia, respectively. However, the surviving animals raised under moderated hypoxia showed a better aptitude to regulate aerobic and anaerobic capacities when exposed to acute hypoxia.

Dating minerals by ID-TIMS geochronology at times of in situ analysis: selected case studies from the CPGeo-IGc-USP laboratory

Since 1964, the Center for Geochronological Research - CPGeo, one of the interdepartmental centers of the Instituto de Geociências (IG) of São Paulo University, has developed studies related to several geological processes associated with different rock types. Thermal Ionization Mass Spectrometry Isotopic Dilution (ID-TIMS) has been the technique widely used in the CPGeo U-Pb Laboratory. It provides reliable and accurate results in age determination of superposed events. However, the open-system behavior such as Pb-loss, the inheritance problem and metamictization processes allow and impel us to a much richer understanding of the power and limitations of U-Pb geochronology and thermochronology. In this article, we present the current methodology used at the CPGeo-IGc-USP U-Pb laboratory, the improvements on ID-TIMS method, and report high-precision U-Pb data from zircon, monazite, epidote, titanite, baddeleyite and rutile from different rock types of several domains of the Brazilian south-southeast area, Argentina and Uruguay.

Biocompósitos de matriz glioxal-fenol reforçada com celulose microcristalina

Glioxal pode ser obtido a partir de biomassa (como da oxidação de lipídeos) e não é tóxico ou volátil, tendo sido por isso utilizado no presente trabalho como substituto de formaldeído na preparação de resina fenólica do tipo novolaca, sendo usado como catalisador o ácido oxálico, que também pode ser obtido de fontes renováveis. A resina glioxal-fenol foi utilizada na preparação de compósitos reforçados com celulose microcristalina (CM, 30, 50 e 70% em massa), uma celulose com elevada área superficial. As imagens de microscopia eletrônica de varredura (MEV) das superfícies fraturadas demonstraram que os compósitos apresentaram boa interface reforço/matriz, consequência da elevada área superficial da CM e presença de grupos polares (hidroxilas) tanto na matriz como na celulose, o que permitiu a formação de ligações hidrogênio, favorecendo a compatibilidade entre ambas. A análise térmica dinâmico-mecânica (DMTA) demonstrou que todos os compósitos apresentaram elevado módulo de armazenamento à temperatura ambiente. Além disso, o compósito reforçado com 30% de CM apresentou baixa absorção de água, comparável à do termorrígido fenólico, que é utilizado em escala industrial. Os resultados demonstraram que compósitos com boas propriedades podem ser preparados usando elevada proporção de materiais obtidos de biomassa.

Photo-fenton degradation of poly(Ethyleneglycol)

Polyethyleneglycol (PEG) was photooxidized in a photo-Fenton system and results compared with the dark reaction. The products were analysed using GPC and HPLC. In the absence of light, PEG samples needed 490 min to reduce their w by 50%, whereas under UV irradiation, only 10 min were necessary. The exponential decay of w with a concomitant increase in polydispersity and number of average chain scission, characterized a random chain scission mechanism. The degradation products of PEG in both systems showed the presence of lower molecular weight products, including smaller ethyleneglycols and formic acid. The mechanism involves consecutive processes, were the larger ethyleneglycols give rise, successively, to smaller ones. This suggests that the mechanism involves successive scissions of the polymer chain. Irradiated samples decomposed faster than those kept in the dark This study proves that the foto-Fenton method associated with UV-light is a good reactant for PEG photodegradation.

The UV/H2O2 - photodegradation of poly(ethyleneglycol) and model compounds

The general mechanism for the photodegradation of polyethyleneglycol (PEG) by H2O2/UV was determined studying the photooxidation of small model molecules, like low molecular weight ethyleneglycols (tetra-, tri-, di-, and ethyleneglycol). After 30 min of irradiation the average molar mass (Mw) of the degradated PEG, analysed by GPC, fall to half of its initial value, with a concomitant increase in polydispersitivity and number of average chain scission (S), characterizing a random chain scission process yielding oligomers and smaller size ethyleneglycols. HPLC analysis of the photodegradation of the model ethyleneglycols proved that the oxidation mechanism involved consecutive reactions, where the larger ethyleneglycols gave rise, successively, to smaller ones. The photodegradation of ethyleneglycol lead to the formation of low molecular weight carboxylic acids, like glycolic, oxalic and formic acids.

Determination and fractionation of barium in Brazil nuts

Several sample preparation strategies were employed for determination and fractionation of barium in Brazil nuts using measurements by graphite furnace atomic absorption spectrometry (GF AAS) and inductively coupled plasma optical emission spectrometry with axial view (ICP OES). This food is widely consumed because of its nutritional value and good taste. The chemical analysis of Brazil nuts is not trivial due to their complex matrix. The fractionation of barium in Brazil nuts was studied owing to the toxicity of this element and the strong correlation between chemical form and absorption. Total concentrations of barium varied from 860 to 2084 mg kg-1. Sequential extractions were performed based on solubility in different media and also according to lipids, proteins and low molecular weight fractions (LMW). The greatest contents of barium were determined in the LMW and in the water insoluble fractions with concentrations in the range 778 to 1606 and 551 to 1520 mg kg-1, respectively. Based on these results it can be inferred that Ba is not absorbed when Brazil nuts are ingested. Considering both the contents of barium and sulfur in different fractions and stoichiometric calculations it was also possible to assume that barium occurs mainly in the BaSO4 form. The presence of this chemical form was also confirmed by thermogravimetric measurements.

Study of C- and O-glycosylflavones in sugarcane extracts using liquid chromatography: exact mass measurement mass spectrometry

The flavonoids present in sugarcane (Saccharum officinarum) extracts were analyzed by liquid chromatography - mass spectrometry (LC-MS), and a study of the fragmentation patterns of selected flavonoids was conducted using orthogonal acceleration time-of-flight electrospray ionization mass spectrometry (ESI-oa-ToF MS). Seven C- and O-glycosylflavones were identified in the extracts, namely, schaftoside, isoschaftoside, luteolin-8-C-(rhamnosylglucoside), vitexin, orientin, tricin-7-O-neohesperidoside and tricin-7-O-glucoside. Of these, five were identified in the absence of direct comparison with their respective standards. The described method also permitted the differentiation of the 6-C and 8-C isomeric flavones, schaftoside and isoschaftoside. The combination of fragmentation data and exact mass measurement showed to be complimentary to the HPLC-UV-MS techniques previously utilized for isomers discrimination in sugarcane studies.

Avaliação do hiperinsulinismo em amostra de crianças pré-puberes

OBJETIVOS: Determinar a relação entre o índice de massa corporal (IMC), o homeostasis model assessment - insulin resistance (HOMA-IR) e a insulinemia. MÉTODOS: Realizou-se um estudo observacional prospectivo transversal com 132 crianças pré-púberes em idade escolar e residentes no município de Santo André (SP). Fez-se a avaliação antropométrica e a mensuração da glicemia, da insulinemia e do índice HOMA-IR. RESULTADOS: Dentre as 132 crianças avaliadas, 78 eram meninas (59,1%) e 54 eram meninos (40,9%), com média de idade de 8,7 anos e média de IMC de 13,7 kg/m². Observou-se uma associação significativa e positiva entre HOMA-IR e IMC, insulina e IMC, peso e HOMA e entre insulina e peso; também foi constatado que, quanto maior for o IMC, maior será o valor de HOMA. CONCLUSÕES: Os resultados do presente estudo permitem concluir que há uma forte associação entre o hiperinsulinismo e a obesidade, devendo ser tomadas algumas medidas para evitar o ganho de peso durante a infância e a adolescência.

Experimental nodel of C6 brain tumors in athymic rats

Malignant brain tumor experimental models tend to employ cells that are immunologically compatible with the receptor animal. In this study, we have proposed an experimental model of encephalic tumor development by injecting C6 cells into athymic Rowett rats, aiming at reaching a model which more closely resembles to the human glioma tumor. In our model, we observed micro-infiltration of tumor cell clusters in the vicinity of the main tumor mass, and of more distal isolated tumor cells immersed in normal encephalic parenchyma. This degree of infiltration is superior to that usually observed in other C6 models.

Extraction and concentration of biogenic calcium oxalate from plant leaves

The objective of this study was to extract and concentrate calcium oxalate (CaOx) crystals from plant leaves that form the above mentioned crystals. The chemical and physical studies of CaOx from plant to be performed depend on an adequate amount of the crystals. The plant used in this study was croton (Codiaeum variegatum). The leaves were ground in a heavy duty blender and sieved through a 0.20 mm sieve. The suspension obtained was suspended in distilled water. The crystals were concentrated at the bottom of a test tube. The supernatant must be washed until it is free of plant pigments and other organic substances. Biogenic CaOx crystals have well-defined and sharp peaks, indicating very high crystallinity. Moreover, the CaOx crystals were not damaged during the extraction procedure, as can be seen on the scanning electron microscope images. The porposed method can be considered efficient to extract and concentrate biogenic calcium oxalate.

Synthesis and structural characterization of block and random low molecular weight copolymers composed of L-lactic acid and isosorbide succinate moieties

Isosorbide succinate moieties were incorporated into poly(L-lactide) (PLLA) backbone in order to obtain a new class of biodegradable polymer with enhanced properties. This paper describes the synthesis and characterization of four types of low molecular weight copolymers. Copolymer I was obtained from monomer mixtures of L-lactide, isosorbide, and succinic anhydride; II from oligo(L-lactide) (PLLA), isosorbide, and succinic anhydride; III from oligo(isosorbide succinate) (PIS) and L-lactide; and IV from transesterification reactions between PLLA and PIS. MALDI-TOFMS and 13C-NMR analyses gave evidence that co-oligomerization was successfully attained in all cases. The data suggested that the product I is a random co-oligomer and the products II-IV are block co-oligomers.